Effects of increased venous pressure on albumin and IgG-excluded volumes in skin

The effect of increased venous pressure on the exclusion of plasma albumin and γ-immunoglobulin G (IgG) in skin interstitium was studied in anesthetized rabbits. In eight rabbits, venous pressure in the left leg was increased from 7 to 26 mmHg, while the right leg served as a control. Samples of plasma and prenodal popliteal lymph were collected for 4 h before taking samples of heel skin. The extracellular and plasma spaces in the tissue samples were measured using ⁵¹Cr-labeled ethylenediaminetetraacetic acid (EDTA) and ¹²⁵I-labeled human serum albumin, respectively. The protein spaces were calculated from measurements of endogenous albumin and IgG concentrations using rocket electroimmunoassay. For control skin, albumin and IgG were both excluded from 50% of the interstitial space. The interstitial space after venous congestion was increased 1.4 times control. There was a washout of interstitial albumin and no change in the albumin-excluded volume fraction. For IgG, there was no change in the extravascular mass and a decrease in the excluded volume fraction. Changes in the interstitial gel matrix of skin were different from those in visceral organs and consistent with a greater amount of collagen.